(a) Field of the Invention
Embodiments of the invention relate generally to touch screen displays. More specifically, embodiments of the present invention relate to a photo sensor, a display device including the same, and a driving method therefor.
(b) Description of the Related Art
The development of touch screen display devices has also entailed development of touch sensors that can be incorporated into such displays. When a user's hand, a touch pen, or the like touches a screen of the display device, the sensor generates an output signal and provides the output signal to the display device. The display device determines touch information such as the presence or absence of touch, a touch position and the like therefrom, to transmit the touch information to an external device. The external device then transmits an image signal to the display device, based on the touch information.
One such sensor is a photo sensor. These sensors, which operate by sensing a change in light due to a touch, are each generally made up of a transistor which is a three-terminal element, and may determine the presence or absence of touch by sensing photo current produced by light irradiated upon a channel unit of the transistor. In this case, when the sensing signal from the photo current is sufficiently small, touch information such as the presence or absence of touch and a touch position may not be correct.
Meanwhile, the sensor may be attached to the display device, or may be formed in the display device. In either case, when a sensing circuit is complicated or overly large, an aperture ratio of the display device may be undesirably reduced.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.